Hmm...or perhaps there is mass planetary destruction on an even larger scale than the previous films. And instead of head crushing, the new villain completely crushes people with some kind of large compacting device. Spock Prime is witnessing all of this. Then Whoopi Goldberg shows up and tells him he's actually still in the prime universe, but none of what he's experienced over the past few years is real. He's in the Nexus. And due to progressing early onset Bendii Syndrome, Spock's nexus is twisted and includes lots of destruction and death. His apparently random romantic involvement with Uhura is something he deep down always wanted. And he's in the Nexus, so there you go. But his extreme emotions due to his condition are telepathically causing the Nexus to expand and cause rips in space/time. So Admiral Chekov (Prime) is sent to the Nexus to investigate what's causing the massive rip in space/time, and then he finds Spock Prime and brings him out of the Nexus (after fighting off the body crushing villain).